stm32l431RC ADC 采集Vbat 不准的问题

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zhaoxuji-239467 发布时间：2020-5-11 13:08

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系统电池供电，3.6V电池，经过一个二极管（3A），大概是3.3V到Vbat .
测量电压为2.98V 左右。
继续采用直流电源供电，当输入Vbat 3.0v 时，测量为 2.86V左右。
同时还发现一些怪现象，aADCxConvertedData[0]，明显比后续的采集值小很多。
哪里操作有问题？

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/* Definition of ADCx conversions data table size */
#define ADC_CONVERTED_DATA_BUFFER_SIZE ((uint32_t)  10) /* Size of array aADCxConvertedData[] */
static uint16_t aADCxConvertedData[ADC_CONVERTED_DATA_BUFFER_SIZE];
/**
  * @brief  Conversion complete callback in non-blocking mode.
  * @param hadc ADC handle
  * @retval None
  */
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
  /* Prevent unused argument(s) compilation warning */
if(BinarySem_ADCHandle)
osSemaphoreRelease(BinarySem_ADCHandle);

  /* NOTE : This function should not be modified. When the callback is needed,
         function HAL_ADC_ConvCpltCallback must be implemented in the user file.
*/
}
/**
  * @brief  测量电池电压
  * @param[IN]
  * @retval None
  */
uint32_t getBattaryTemperatureMeasure(uint8_t bat_flag)
{
   ADC_ChannelConfTypeDef sConfig = {0};

   memset(aADCxConvertedData,0,sizeof(aADCxConvertedData));
   /* ### - 1 - Initialize ADC peripheral #################################### */
   hadc1.Instance       = ADC1;
   if (HAL_ADC_DeInit(&hadc1) != HAL_OK)
   {
      /* ADC de-initialization Error */
      Error_Handler();
   }

   hadc1.Init.ClockPrescaler       = ADC_CLOCK_SYNC_PCLK_DIV1;    /* Synchronous clock mode, input ADC clock divided by 2*/
   hadc1.Init.Resolution          = ADC_RESOLUTION_12B;          /* 12-bit resolution for converted data */
   hadc1.Init.DataAlign          = ADC_DATAALIGN_RIGHT;          /* Right-alignment for converted data */
   hadc1.Init.ScanConvMode       = DISABLE;                      /* Sequencer disabled (ADC conversion on only 1 channel: channel set on rank 1) */
   hadc1.Init.EOCSelection       = ADC_EOC_SINGLE_CONV;          /* EOC flag picked-up to indicate conversion end */
   hadc1.Init.LowPowerAutoWait    = DISABLE;                      /* Auto-delayed conversion feature disabled */
   hadc1.Init.ContinuousConvMode = ENABLE;                      /* Continuous mode enabled (automatic conversion restart after each conversion) */
   hadc1.Init.NbrOfConversion    = 1;                            /* Parameter discarded because sequencer is disabled */
   hadc1.Init.DiscontinuousConvMode = DISABLE;                      /* Parameter discarded because sequencer is disabled */
   hadc1.Init.NbrOfDiscConversion = 1;                            /* Parameter discarded because sequencer is disabled */
   hadc1.Init.ExternalTrigConv    = ADC_SOFTWARE_START;          /* Software start to trig the 1st conversion manually, without external event */
   hadc1.Init.ExternalTrigConvEdge  = ADC_EXTERNALTRIGCONVEDGE_NONE; /* Parameter discarded because software trigger chosen */
   hadc1.Init.DMAContinuousRequests = ENABLE;                      /* ADC DMA continuous request to match with DMA circular mode */
   hadc1.Init.Overrun             = ADC_OVR_DATA_OVERWRITTEN;    /* DR register is overwritten with the last conversion result in case of overrun */
   hadc1.Init.OversamplingMode    = DISABLE;                      /* No oversampling */
   /* Initialize ADC peripheral according to the passed parameters */
   if (HAL_ADC_Init(&hadc1) != HAL_OK)
   {
      Error_Handler();
   }

   /* ### - 2 - Start calibration ############################################ */
   if (HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED) !=  HAL_OK)
   {
      Error_Handler();
   }

   /* ### - 3 - Channel configuration ######################################## */
   sConfig.Channel    = ADC_CHANNEL_VBAT;             /* Sampled channel number */
   sConfig.Rank       = ADC_REGULAR_RANK_1;       /* Rank of sampled channel number ADCx_CHANNEL */
   sConfig.SamplingTime = ADC_SAMPLETIME_6CYCLES_5; /* Sampling time (number of clock cycles unit) */
   sConfig.SingleDiff = ADC_SINGLE_ENDED;          /* Single-ended input channel */
   sConfig.OffsetNumber = ADC_OFFSET_NONE;          /* No offset subtraction */
   sConfig.Offset = 0;                               /* Parameter discarded because offset correction is disabled */
   if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
   {
      Error_Handler();
   }

   /* ### - 4 - Start conversion in DMA mode ################################# */
   if (HAL_ADC_Start_DMA(&hadc1,
                        (uint32_t *)aADCxConvertedData,
                        ADC_CONVERTED_DATA_BUFFER_SIZE
                        ) != HAL_OK)
   {
      Error_Handler();
   }
   uint32_t ret = 0 ;
   if(osOK == osSemaphoreWait(BinarySem_ADCHandle,10))
   {
   uint32_t adc_val = 0;//aADCxConvertedData[1];
   for (int i = ADC_CONVERTED_DATA_BUFFER_SIZE/2 ; i < ADC_CONVERTED_DATA_BUFFER_SIZE ; i++)
   {
   adc_val += aADCxConvertedData;
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   adc_val = adc_val  / (ADC_CONVERTED_DATA_BUFFER_SIZE/2);# X# D# K  F5 a; S1 y' ~
   ret = __HAL_ADC_CALC_DATA_TO_VOLTAGE(2500,adc_val,ADC_RESOLUTION_12B);2 H' ^) W6 J) k6 J5 P
   ret *= 3;
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   return (ret);5 g2 Q2 M$ X* C: e/ h& u3 E  S
}
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